Alloy composition



. May 9,1967

G. S. FOERSTER ET AL ALLOY COMPOSITION Filed Dec. 50, 1964 s 09 O u? m b O W/. percen/an/l'mony INVENTORS. George 6. Foams/er Edwarc/L.

flTTOR/VEY United States Patent M 3,318,693 ALLOY COMPOSITION George S. Foerster, Midland, Mich., and Edward L. Hill,

Littleton, Colo., assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware Filed Dec. 30, 1964, Ser. No. 422,363 2 Claims. (Cl. 75-153) This invention relates to copper base alloys and in particular relates to low melting copper base alloys having appreciable ductility.

Conventional copper casting alloys have a liquidus temperature above, for example, about 160 0 F. They are, therefore, difficult to die cast in that these cause considerable wear on the die. Known copper base alloys which, on the other hand, melt at lower temperatures are too brittle for practical use in die casting. For example, the copper base alloy containing 9.7 weight percent of magnesium melts at about 722 C. (1332 F.) while the copper base alloy containing 31 weight percent of antimony melts at only 645 C. (1193 F.); both alloys are very brittle, that is, they have little, if any, ductility.

The object of the present invention, therefore, is to provide a ductile, low melting, copper base alloy.

It is another object of the present invention to provide a novel, ductile, low melting copper base alloy particular- 1y suit-able for use in die casting operations.

The above and other objects and advantages have surprisingly been found obtainable in a copper base alloy containing both magnesium and antimony in critical proportions.

The figure is a graph illustration defining the present novel alloy.

The present invention is a novel, low melting, antimony and magnesium-containing copper base alloy having appreciable ductility properties comprising the compositions lying within quadrilateral area ABCD, bounded by lines, AB, BD, CD, and CA of the figure. As shown, the antimony content ranges from about 5 to about 25 weight percent. Magnesium at the 5 percent antimony level ranges from about 1 to about 4.5 weight percent increasing such that when antimony is at the maximum of about 25 percent, the magnesium content of the alloy ranges from about 6.5 to about 1-0 weight percent, the balance being essentially copper.

Preferably, the present alloy will comprise the composition lying within the quadrilateral area EFGH, bounded by lines EF, FG, GF, and HE of the figure. As shown,

the antimony content in these preferred alloys ranges from about to about weight percent. The magnesium content at the 15 percent antimony level ranges from about 4.5 to about 6.0 weight percent increasing such that when the antimony content approaches 20 per- 50 cent the magnesmm content in the alloy ranges from 3,318,693 Patented May 9, 1967 ICC about 6.0 to about 7.5 percent, the balance being essentially copper.

The appreciable ductility of the present novel alloys is surprising in that when both antimony and magnesium are separately alloyed within the above range with copper the resulting alloys are quite brittle, whereas if both are alloyed together in copper base metal, a low melting copper base alloy is obtained having a totally unexpected appreciable ductility. All the novel alloys in the preferred range of ingredients of the present invention have a melting point as low as about 720 C. Decreasing the antimony and magnesium content within the broad composition limits of the invention tends to improve ductility but increases the liquidus temperature.

In preparing the alloys of the present invention, conventional melting and alloying techniques are employed. Normal care is exercised to avoid excessive or detrimental oxidation of the magnesium additive as is understood by one skilled in the art.

The following examples serve to more fully illustrate the preparation, utility, and character of the present novel copper base alloys, but are not to be construed as limiting the invention thereto.

Examples A number of alloys were prepared by first melting down copper in an induction furnace to make several 1000 gram melts. Antimony and magesium were then alloyed with the copper in varying amounts, both separately (as controls) and together (as controls as well as to provide working examples of the present novel alloy composition). In preparing some of the alloys, charcoal was added to the copper-antimony melt, which melt was then heated prior to adding the magnesium component. This removed excess oxygen and other gases from the metal. Thereafter, the magnesium was then added and stirred in, whereupon, the molten composition was cast into raw samples using a inch diameter graphite mold. In preparing other samples the magnesium component was first melted under a suitable flux cover with the copper being added to the molten magnesium while increasing the temperature. The antimony was added last. Argon was then bubbled through the molten composition to remove dissolved gases such as, for example, hydrogen, whereupon, each melt was cast in the inch molds. A few melts were also prepared under vacuum by melting all the ingredients together in a 1 /2 inch crucible and allowing the melts to cool and solidly therein. In all cases test samples were prepared and tested at room temperature, either in the as cast condition (F) or after being solution heat treated at 1200* F. for varying periods of time. The properties determined included percent elongation (percent E), tensile yield strength (TYS), and tensile strength (TS). The results of these tests are presented in Tables I and II below.

TABLE I.MELTS MADE WITH THE INDUCTION UNIT Composition by Wt. 1,000 p.s.i. Examples Temper 2 Percent E Results Percent Sb Percent Mg TYS TS Control A l0 15 Brittle. Control B 6 19 Do. 1 10 5 31 Good ductility. 2 15 6 35 Ductile. 3 20 7 35 Do. 4 20 7 29 Do. Control C 20 5 14 Brittle. Control D 18 3 6 Do. Control E 17 3. 4 23 Do.

1 Balance copper. 2 F=as cast. T4:2% hours at 1,200 F.

5 The properties in Table I illustrate the surprising synergistic effect obtained from the addition of both antimony and magnesium to copper. As shown in Controls A and B, the addition of, for example, either 10 percent 4+ The values given in Table 11 further illustrate the appreciable ductility obtained where the alloys were prepared under vacuum. It should be noted here that the most concentrated alloy of those prepared (Example 7) antimony or 6 percent magnesium severely em-brittles the 5 (whether by use of an induction furnace or under a vacucopper; however, the addition of both 1 percent antium) still had appreciable ductility, notwithstanding the mony and percent magnesium unexpectedly provides larger casting diameter (1 /2 inch) and the slow solidifiappreciable ductility to the composition as evidenced by cation rate. the property values given for Example I of Table I. The present invention can be modified and changed Moreover, as shown by Examples 2 and 3, the appreciwithout departing from the spirit or scope thereof and it able ductility together with the high tensile strength is is understood that the invention is only limited as deretained even if the antimony content is increased to 20 fined in the appended claims. percent and the magnesium content is raised to 7 per- We claim: cent. Heat treatment provides a little improvement in 1. A copper base alloy comprising antimony and magductility as shown by Example 4 of Table I. nesium, the balance being essentially copper, said all-0y TABLE II.-VACUUM MELTs Composition by Wt. (F) 1 1000 p.s.i. (T4) 2 1000 p.s.i.

percent Example Percent Sb Percent Mg Percent E TYS TS Percent E TYS TS l F=As cast. 2 T4=l6 hours at1,200 F.

having a composition by weight within the composition range represented by the area ABCD, bounded by lines AB, BD, CD, and CA of the graph in the appended drawing.

2. A copper base alloy comprising antimony and magnesium, the balance being essentially copper, said alloy having a composition by weight within the composition range represented by the area EFGH, bounded by lines E-F, FG, GH, and HE of the graph in the appended draw- DAVID L. RECK, Primary Examiner.

C. N. LOVELL, Assistant Examiner, 

1. A COPPER BASE ALLOY COMPRISING ANTIMONY AND MAGNESIUM, THE BALANCE BEING ESSENTIALLY COPPER, SAID ALLOY HAVING A COMPOSITION BY WEIGHT WITHIN THE COMPOSITION RANGE REPRESENTED BY THE AREA ABCD, BOUNDED BY LINES 